Solvothermally‐Prepared Cu 2 O Electrocatalysts for CO 2 Reduction with Tunable Selectivity by the Introduction of p‐Block Elements

The electroreduction of CO 2 to fuels and chemicals is an attractive strategy for the valorization of CO 2 emissions. In this study, a Cu 2 O electrocatalyst prepared by a simple and potentially scalable solvothermal route effectively targeted CO evolution at low‐to‐moderate overpotentials [with a current efficiency for CO (CE CO ) of ca. 60 % after 12 h at −0.6 V vs. reversible hydrogen electrode, RHE], and its selectivity was tuned by the introduction of p‐block elements (In, Sn, Ga, Al) into the catalyst. SEM, HRTEM, and voltammetric analyses revealed that the Cu 2 O catalyst undergoes extensive surface restructuring (favorable for CO evolution) under the reaction conditions. The modification of Cu 2 O with Sn and In further enhanced the current efficiency (CE) for CO (ca. 75 % after 12 h at −0.6 V). In contrast, the introduction of Al altered the selectivity profile of the catalyst significantly, decreasing the selectivity toward CO but promoting the reduction of CO 2 to ethylene (CE≈7 %), n ‐propanol, and ethanol (CE≈2 % each) at −0.8 V vs. RHE. This result is related to a decreased reducibility of Al‐doped Cu 2 O that might preserve Cu + species (favorable for C 2 H 4 production) under the reaction conditions, which is supported by XRD, X‐ray photoelectron spectroscopy, and H 2 temperature‐programmed reduction observations.